Long-term carbon and nitrogen dynamics at SPRUCE revealed through stable isotopes in peat profiles [electronic resource]
Environmental Molecular Sciences Laboratory.
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| Format: | Government Document Electronic eBook |
| Language: | English |
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Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2017.
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| Summary: | Environmental Molecular Sciences Laboratory. |
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| Abstract: | <p>Peatlands encode information about past vegetation dynamics, climate, and microbial processes. Here, we used <i>δ</i><sup>15</sup>N and <i>δ</i><sup>13</sup>C patterns from 16 peat profiles to deduce how the biogeochemistry of the Marcell S1 forested bog in northern Minnesota responded to environmental and vegetation change over the past ̃10 000 years. In multiple regression analyses, <i>δ</i><sup>15</sup>N and <i>δ</i><sup>13</sup>C correlated strongly with depth, plot location, C/N, %N, and each other. Correlations with %N, %C, C/N, and the other isotope accounted for 80 % of variance for <i>δ</i><sup>15</sup>N and 38 % of variance for <i>δ</i><sup>13</sup>C, reflecting N and C losses. In contrast, correlations with depth and topography (hummock or hollow) reflected peatland successional history and climate. Higher <i>δ</i><sup>15</sup>N in plots closer to uplands may reflect upland-derived DON inputs and accompanying shifts in N dynamics in the lagg drainage area surrounding the bog. The Suess effect (declining <i>δ</i><sup>13</sup>CO<sub>2</sub> since the Industrial Revolution) lowered <i>δ</i><sup>13</sup>C in recent surficial samples. High <i>δ</i><sup>15</sup>N from -35 to -5 cm probably indicated the depth of ectomycorrhizal activity after tree colonization of the peatland over the last 400 years, as confirmed by the occasional presence of wood down to -35 cm depth. High <i>δ</i><sup>13</sup>C at ̃4000 years BP (-65 to -105 cm) could reflect a transition at that time to slower rates of peat accumulation, when <sup>13</sup>C discrimination during peat decomposition may increase in importance. Low <i>δ</i><sup>13</sup>C and high <i>δ</i><sup>15</sup>N at -213 and -225 cm (̃8500 years BP) corresponded to a warm period during a sedge-dominated rich fen stage. As a result, the above processes appear to be the primary drivers of the observed isotopic patterns, whereas there was no clear evidence for methane dynamics influencing <i>δ</i><sup>13</sup>C patterns.</p> |
| Item Description: | Published through SciTech Connect. 05/17/2017. "pnnl-sa--126833" "49729" "KP1704020" Biogeosciences (Online) 14 9 ISSN 1726-4189 AM. Erik A. Hobbie; Janet Chen; Paul J. Hanson; Colleen M. Iversen; Karis J. McFarlane; Nathan R. Thorp; Kirsten S. Hofmockel. |
| Physical Description: | p. 2481-2494 : digital, PDF file. |